The use of electrical and hydraulic controllers as a means for the selective control of valves in large irrigation systems having a plurality of independent branches or lines is widespread. Such controllers have been employed in farming applications, large real estate development projects, golf courses, and a myriad of other irrigation applications. The irrigation systems usually are comprised of a source of water, a plurality of independently operable irrigation branches connected to the water supply, a valving network or system and a controller, which is formed and connected to selectively open and close valves so that water can be communicated to various sprinkler heads or other water outlets for a known period of time. Such controllers may either be electronic and coupled to solenoid valves or fluid (usually hydraulically) actuated and connected to correspondingly formed valves. Either kind of controller will virtually always include a timing mechanism enabling irrigation of various areas in the multi-branched system on a programmed or pre-planned basis.
The following United States patents are illustrative of irrigation systems which employ a central controller to enable selective irrigation of individual branches in a multi-branched irrigation system: U.S. Pat. Nos. 3,578,245, 3,599,867, 3,653,595 and 3,726,477. The first three of these patents disclose systems in which the master controller is directly wired to either a solenoid valve or to slave stations which control operation within a branch or irrigation zone. U.S. Pat. No. 3,726,477 is similar in nature except that instead of providing for wiring back to a central controller, the central controller includes a radio transmitter which is used to broadcast signals from a central location to satellite or slave stations. The command signals from the central transmitter are encoded so as to activate only selected ones of the slave receivers, but the system basically substitutes radio transmission for the completely wired systems previously employed.
In addition to the four above set forth patents, U.S. Pat. Nos. 3,227,219 and 3,420,270, relating only peripherally to sprinkler systems and multi-branch irrigation controllers, were located during preliminary patent research.
Unfortunately, any large irrigation system will experience a certain number of failures, and the above set forth irrigation systems and controllers are not designed or well suited to deal with such failures. Whether the controller is one which depends on electric wires, radio transmission or hydraulic lines, the problem is the same, namely, the failure occurs at a location which is remote from the controller. The current process for repairing lines requires a man located at the controller and a second man located in the field who does the repair work. On command from the person in the field, the controller can be used to turn on the water and open and close valves until it is directed to the affected branch of the irrigation system. Once the trouble spot is located, the man in the field directs the man at the controller to shut down the system for repairs, and after the repairs are made, the man in the field directs the man on the controller to turn on the system for testing. Many times, distance or the presence of buildings or other obstructions makes visual and unaided audio communication impossible. Accordingly, such testing often requires that both men additionally have special communications equipment, such as a walkie-talkie, to enable communication of the commands. Unfortunately, some repairs may require a very substantial period of time and thereby tie up two men and their associated equipment undesirably, although only one is actually doing the work.